Fay had originally planned to survey Southern Sudan as part of his 2004 "Africa Megaflyover," in which he flew some 70,000 miles (113,000 kilometers) to study humanity's impact on Africa. But U.S. sanctions on Sudan prevented him from getting a license to fly over the country.

He, Elkan, and Marjan wanted to copy aerial surveys conducted between 1981 and 1983 that showed that the region—which has spent 13 of the past 17 decades at war—was teeming with elephants, lions, buffalo, and antelope, along with millions of wintering migratory birds.

Marjan had done ground surveys of the area in 2001 and 2002, while the area was still embroiled in war. He concluded that the white-eared kob had survived in great numbers.

But that work was done on foot, and researchers lacked a more definitive count of migratory animals.

"No one had done any surveys, and in species that are so mobile, the very movement of the herds over so large an area makes it hard to gauge without doing a count," said David Western, a former chief of the Kenya Wildlife Service who had taken a census of kob in 1978.

But the latest results delivered bad news as well. West of the Nile River, in the Southern National Park, wildlife levels suffered near-apocalyptic declines.

Some 60,000 buffalo were counted there in the 1980s. Today, Elkan said, none were found.

And previously, elephant populations were 10,000, but the new surveys found only one group.

Rare white rhinoceroses spotted before were nowhere to be seen.

East of the Nile—where quick-moving animals such as the kob, the Mongalla gazelle, and the tiang survived—more sedentary animals fell victim to poachers and rebels with the Sudan People's Liberation Army, which was living off the land.

There was almost no sign of the 30,000 zebras reported to have been there in the early 1980s, for example.

Crucial Test

Over the past few decades wildlife numbers have plummeted across Africa, with both rich and poor countries largely failing to meet similar challenges.

So the Wildlife Conservation Society and Southern Sudan say they hope the announcement of the survey findings will add momentum to the fledgling government's efforts to develop a proper wildlife policy.

The Wildlife Conservation Society signed a cooperation agreement to help the government come up with a conservation strategy that would include training former soldiers as park rangers and wildlife officers.

"All this cannot be shouldered by the government of Southern Sudan alone," said Alfred Akwoch, undersecretary of the Ministry of the Environment, Wildlife Conservation, and Tourism. "So if there are friends of wildlife of Southern Sudan, they must come and help."

The news that so many animals survived will also test the young government's commitment to wildlife preservation at a time when it wants to exploit vast oil reserves. Widespread seismic exploration has already taken place, some of it in areas inhabited by wildlife.